As the fermentation process for producing L-arginine by using glutamic acid-producing coryneform bacteria of the genus Corynebacterium, Brevibacterium or the like, there have been known processes in which mutants derived from wild type strains of such genus are used. Examples of these L-arginine-producing mutants include strains endowed with resistance to amino acid analogues or nucleic acid analogues, which may optionally be further endowed with nucleic acid base-requirement, as described in Agric. Biol. Chem., 36, 1675-1684 (1972), Japanese Published Examined Patent Application No. 37235/79 and Japanese Published Unexamined Patent Application No. 150381/82.
Further, it is known that strains constructed by recombinant DNA technology can be used for producing L-arginine. For example, L-arginine can be produced by introducing a recombinant plasmid DNA including a DNA fragment containing a gene of an enzyme relating to the biosynthesis of arginine and derived from Escherichia coli in a strain of the genus Corynebacterium or Brevibacterium by and Culturing the transformant thus obtained (Japanese Published Unexamined Patent Application No. 66989/85).
With the increasing demand for L-arginine in recent years, further improvement in the process for producing this amino acid has been desired.
As a result of intensive studies to increase the L-arginine productivity of a microorganism belonging to the genus Corynebacterium or Brevibacterium by recombinant DNA technology, it was found that productivity could be increased by introducing a recombinant plasmid (pEarg1) containing a gene of Escherichia coli that codes for an enzyme relating to the biosynthesis of L-arginine to a strain of the genus Corynebacterium or Brevibacterium (Japanese Published Unexamined Patent Application No. 66989/85). Further studies have now revealed that strains with higher L-arginine productivity as compared with pEarg1-carrying strains can be obtained by introducing in a microorganism of the genus Corynebacterium or Brevibacterium a recombinant plasmid containing a gene that relates to the synthesis of at least one enzyme selected from the group consisting of those relating to the biosynthesis of L-arginine in a microorganism of the genus Corynebacterium or Brevibacterium, particularly, N-acetylglutamate kinase (hereinafter abbreviated to AGK), N-acetyl-.gamma.-glutamyl-phosphate reductase (hereinafter abbreviated to AGPR), N-acetylornithine-.delta.-aminotransferase (hereinafter abbreviated to AOAT), ornithine carbamyltransferase (hereinafter abbreviated to OCT), an enzyme having an activity to alter N-acetylglutamate synthetase (hereinafter abbreviated to AGS)-deficient mutants of Escherichia coli which have arginine-requirement to non-arginine-requiring strains, and an enzyme having an activity to alter N-acetylornithine deacetylase (hereinafter abbreviated to AOD)-deficient mutants of Escherichia coli which have arginine-requirement to non-arginine-requiring strains. The present invention has been accomplished based on these findings.